This was the key to finding the secret. It's a URL path that can take you to a specific image shared here on the forums. Normally there are 6 digits at the end of the path that determine where URL will take you, but here the last 5 digits of the URL were missing.
Clicking on most of the fruits wouldn't help but the second green apple (the only fruit not in Terraria) would take you to this image (next pfp).